slough



F. M. SLOUGH. TELEPHONE swncuma SYSTEM.

APPUCATION FILED AUG. I2. 1918. 1,324,750. Patented Dec. 9,1919.

2 SHEETS-SHEET 1- INVENTOR F. M. SLOUGH.

TELEPHONE SWITCHING SYSTEM.

APPLICATION FILED Aug. l2. I918.

1 $24,750 Patented Dec. 9, 1919.

2 SHEETS-SHEET 2- INVENTOR WMW UNITE srarns PATENT ouuron FRANK M. snouen, or RocHnsrER, NEW YORK, AssrGNoR TO THE STROIVIBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, or Rooi-rEsTER, NEW YORK, a CORPORATION on NEW YoRK. I

TELEPHONE SWITCHING SYSTEM.

Specification of Letters Patent. Patgnted Dec, 9, 1919,

Application filed August 12, 1918. Serial N o. 249,501.

To all whom it may concern:

Be it known that I, FRANK M. SLorroH, a citizen of the United States, residing at Rochester, Monroe county, State of New York, have invented certain new and useful Improvements in Telephone Switching Systems, of which the following is a specifica 'to maintain the connection until the end of the conversational period.

Another object is to provide a group of relays with auxiliary apparatus in unitary structures which may be individual to a telephone line without the use of an excessive amount of common apparatus and with the use of only such common apparatus as is positive in operation and not interfering between the various lines connected to the system.

Other objects of my invention and the invention itself will be apparent as the description progresses. Referring to the drawings accompanying this specification Figure 1 shows the circuits and arrangement of the diagrannnatical arrangement of the apparatus involved in a preferred embodiment of my invention.

Fig. shows a side view of a relay selector switch mechanism embodying my invention.

Fig. 3 shows an ens view of the device shown in Fig. 2. 7

Referring to Fig. l at A, I show a telephone substation located on a line Ll, terminating in central office lme apparatus LS. At H, I show a connector switch trunk circuit mechanism of the usual type, certain modifications and improvements being therein included however to more fully carry out the purposes of my invention.

sit L-2, I show a called line upon which is located a telephone substation B, the called line likewise terminating in line switch apparatus LS. 2, a portion of which only is shown but the remaining portion not shown is understood to be the same as that'shown at LS. Although I show only one connector switch circuit at H, it is understood that in practice many would be employed, the indrawing and above referred to are indicated at 123 for the trunk circuit H 2; 4.-'56 for the trunk circuit H, theother sets of corresponding relay line switch contacts for the other trunk circuits being shown at OS. 3, (1S. e, and at (1S. 5. In

the operation of the system it is understood that only'one set of relay line switch contacts of a given line switch will be at any one time operated.

Small controlling magnets for the above sets of line switch contacts are shown at LM. 1, LM. 2, LM. 3, LM. 4 and LM. 5 A similarly disposed and similarly operating magnet Lfti. is arranged to control the set of contacts comprising contacts C-6, 12, 13, 14, '15 and 16.

This line switch magnet LM. and its controlled contacts become connnon to the relay line switch mechanism and common to the group, of trunk switch magnets and their controlled contacts. A line relay LR. and a controlling latch relay CL. is provided for the line circuit and common to the group of line magnets above referred to.

At W-l and "W2 I show 2 traveling switch wipers preferably rotatablymounted on a common shaft and having anumber of operative positions corresponding to the number of trunk circuits, such as the trunk circuit H which are common to a group of lines served by the said trunk circuits. The

wipers IV1 and lV2 are advanced from one operative position to another on the back stroke of the stepping magnet SML. which stepping magnet is arranged to interrupt its own circuit when its armature is attracted.

wiper W 2 at the time rests, the cir- .cuit arrangements in the trunk circuits such as H being such that an open ative circuit for the stepping magnet SML. is accomplished whenever the switch wiperVV2 rests upon a contact of a busy trunk circuit to cause the stepping magnet to advance the wiper and its associated wiper W1 to the contacts or" the next succeeding trunk circuit so that when the wipers finally come to rest they will rest upon contacts of an idle trunk circuit.

The wiper -1 is provided for the pun pose or" selecting the proper selective line magnet of a calling line circuit, to pre-select the trunk circuit such as the trunk circuit H, to extend a telephonic connection from the calling line such as L1 to the called line L2. Terminals for a connection from a trunk circuit to the lines when they are called lines appear at 17 for the line L'l and at 18, 19, 20 and 21 for the line L2.

Referring to Figs. 2 and 3 at CL. 1 show a controlling latching magnet for the relay selector mechanism or my invention and at LM. 1, LM. 2, LM. 3, LM. a and LM. 5, I show trunk circuit selector magnets for the relay selector and at LM. I show a controlling magnet for the relay selector whose purpose ill be made apparent as the description progresses.

Armatures such as Al, i i-2 A-3, A-l, A5 and A6 are provided for the group of magnets LM. to LM. 5 inclusive, each armature being provided with a latch catch LC.

In F 3 portions of the armatures and associated parts including portions of magnets LM. 3 and LM. l for the said magnets are shown broken away to more clearly expose the operating latching magnet CL. and portions of its armature A and associated contact spring set SA. retractal spring S. together with associated apparatus.

' A set of contact springs CS. 1, CS. 2, (1S. 3, CS. 4-, CS. 5 and CS. 6 are provided for the armatures A1 to A6 inclusive and an additional set of contacts C6 is provided for the armature A6 which contact set is operated whenever the said armature is attracted clue to the energization of in controlling magnet LM.

In order to carry out the purposes of my illVBiitiOll the mechanism of the selector switch shown in Figs. 2 or 8 is so arranged hat by causing the energization of any eat the small magnets LM. to LM. 5 inclusive to attract its assoc t d armature and by energizing the COZltl'Ol latching magnet CL. to attract its armatine A that any one of the attracted armatures such as Ltd. will have its latch catch LC. latch on the end of the latching armature A so that upon a succeeding deenergization of the magnet CL. the latched armature will be lifted vertically, operating its associated set of springs such as for instance the set oi springs CS. 1. l he previously energized selector magnet such as for instance the magnet LM.. 1 may now be deenergized, the spring set as CS. 1 reinaining operated due tothe retractal force of the spring S secured to the armature'A which withdraws this armature to its normal position after having been attracted by its operating magnet CL. Now, whenever it is desired to release the operated spring set such as the spring set CS. it is only necessary to cause a momentary operation of the magnet CL. to unlatch the catch member LC. of the latched in armature.

To facilitate a better understanding of my invention a descriwion of the embodiment illustrated will now be each particular reference being made to figure 1, the description being made plainer if desired by reference to the other figures the same reference characters being usedin all of the figures. The subscriber A will initiate a call by removing his receiver from the hook closing the line circuit of the line L1 through a circuit interrupter D which may be the well known form of automatic calling dial and a substation talking apparatus shown in the usual conventional iorm. lnclosure of the line circuit will thereupon operate the line relay LR. through normal contacts 16 and let, a source of current being included in this circuit and shown at Bl, the line relay th reupon being energized will attract its armatures closing contacts in the circuits of the line switch magnets LM. 1 to LM. 5 inelusive but only one or these magnets will be energized, the particular one energized depending upon the position of the switch wiper -W1 which completes the circuit of one of them in the position illustrated. this one being the magnet Ll /l. 2. included in circuit with this selected line magnet LM. 2

through contacts of the line relay LR. and through the presclect ng switch wiper /V-l is the line magnet LM. common to the group of magnets LM. 1 to LM. 5, which magnet L. will operate at the same time as magnet LM. 2. The magnets Lid. and

LM. 2 being encr ized will attract their armatures condition 3g their latch catches LC. to be latched by the armature A of the controlling magnet CL. after the controlling magnet CL. is energized. This now I the controlling magnet CL. being energized subsequent to the energizaticn of the magnet Lit i. since LM. attracts its armature, closing contacts C6 in the circuit of the controlling magnet CL. together with a source or current. Current from the said source will flow over this circuit which may be traced as follows. From the ground pole of batte "y through contacts C6 ofthe magnet LM. normal contacts 12- ot the set associated with the magnet LEVI. normal contacts SA. and the winding of the controlling magnet CL. to the negative pole of the source of the current. This will cause the energiz'ation of the magnet CL. which will attract its armature A and due to the opening of the contacts SA. in its circuit,

.the magnet CL. will immediately again release its armature A to liftthe locked in armatures A2 and A6 whose latch catches LC, are advanced to their latching position due to the attraction of their magnets LM. and LM. 2 upon the armatures A2 and A6 and will operatethe' spring sets CS 2 and OS. 6. e The spring set (15. (ibeing operated will cause the breaking of contacts l2 which will open the circuit of the magnet CL. so that it will not again be operated unless perchance the latch catch LC. of the attracted armature A6 was not at the first efiort, latched, in which case the action would be repeated.

At the same time that the contacts 12 were opened other contacts of the set of contacts (1S. 6 were also operated. The contacts 14 and 16 areto perform the same function as the break contacts of the conventional line cut off relay of the art, namely, to disassociate the line relay andall connections to ground from the line talking conductors.

Contacts 13 are closed to provide a release circuit for the line switch as will be made later apparent as the narrative progresses.

The set of contacts comprising con-tact pairs 15 and 115 are-operated'to make the multipled connector contacts 17 of the line test busy, should a call bemadc by some other station of the system forv the line L1.

The method by which this is accomplished will later be made apparent but for the present it is suflicient to state that the third connector contact of the set'17 counting from the top, called the test contact-by the operation of this set of contacts is connected to ground through the contacts 115 whlcn are now closed and the connectlon to battery through the line magnet L.M.:1s removed from'the said testcontact.

At the same time that the spring contact set CS. 6 was operated the spring contact set CS. 2 was also operated, closing contact pairs 5 and 6 to extend the line conductors of the line L-l to the talking strands, 22 and 23 of the trunk circuit H, which trunk circuit is herein illustrated as being a connector switch trunk circuit, in which the outgoing conductors are connected to traveling s'witch contacts directively operated un der the control of the calling subscribers dial. The pair of contacts a being closed will extend the release circuit which includes the winding of the controlling magnet CL.

of the calling line circuit through now closed contacts 13, of the contact set US. 6 and the contacts 4 to normally opened contacts of a release relay RL. of the trunk circuit H which normally opened contacts at this time remain open since, and will so remain until the end of the connective period. p

The talking strands of the line circuit L1 are extended through now closed contact pairs 4 and 5 of the set CS. 2 to the talking strands 22 and 23 of the connector switch circuit and the subscribers' instrument remaining across the talking strands of the line circuit will complete a circuit including the said subscribers instrument and the source of current over the strands 22'and 23 of the connector switch, an impedance battery feed coil 24 and the impulse relay winding 25 connected to ground and the negative pole of battery respectively. Current flowing through the impulse relay winding will cause the relay to attract its armatures closing contacts 26 and 27 and opening contacts 28 for purposes which will appear.

The contacts 27 being closed will con1 plete a circuit including the source of current for the slow releasing interval relay SR1, the circuit being traced from the ground pole of battery through the contacts 27, winding of the relay SR1. through the first position contacts of the side switch wiper 29 to the negative pole of battery.

he slow releasing impulse relay SR1. will thereby attract its armatures, closing contacts 30 and 31 and opening contacts 32 for purposes which will later-appear. The

closure of the contacts 26 and ot the con tacts 30 of the relays 25 and SR1. both place a ground connection upon the circuit conductor 33 leading to the contact 34: of the preselection switch wiper vV2 which at the time is resting upon the said contact 34: and the ground connection being applied will complete a circuit for the stepping magnet SML. for the preselection switch to cause the preselection switch wipers 7-1 and W-2 to advance to their next resting position whereupon they will makecontact with circuit conductors 35 and 36 which are associated with the trunk circuit H3 to preselect trunk H3 for a succeeding call.

The wiper VV1 leaving the contact 37 will remove the ground connection from the selector magnets, such as the selector magnet LM. 2 which selector magnets are associated with the trunk circuit H so that on a ground potential upon the contact 85 of the assumed busy trunk circuit 11-3 so that the preselector switch wipers will advance from trunk point to trunk point until they finally come to rest upon the contacts of an idle trunk circuit.

The trunk connector switch circuits are now conditioned for the dialing operation by the subscriber by means of which the subscriber can control the movement of the traveling switch contacts of the connector switch H to cause them to make connection with contacts connected to the called desired line terminals. The subscriber now by operating his dial to a degree determined by the first digital designation of the called line number will interrupt the circuit of the line Ll a predetermined number of times depending upon the degree of operation of the dial.

Upon the first opening of the line circuit by the calling subscribers dial, the contacts 27 will be momentarily opened and the contacts 28 momentarily closed, the armature vibrating rapidly back to its operated position, the process being repeated rapidly a predetermined number of times in accordance with the number of times the line circuit is opened by the calling subscribers dial.

The relay SR1. will remain energized during this period since it is of the wellknown slow releasing type and only allows its armatures to be retracted slowly. Upon the first retraction of the armatures of the relay 25, a circuit is closed for the slow releasing relay S.R.R., the circuit being traced from the ground pole of battery to the normal contacts 28 of the impulse relay 25 through now made contacts 31 of the relay SR1. which maintains its armatures attracted during this period through the winding of the relay SRR. and through the winding of the primary stepping magnets PM. of the connector switch through first position contacts of the side switch wiper 10 to the negative pole of the source of current. This circuit is closed once for every time that the line is opened duringthe sending of the first series of impulses by the calling subscriber and for each opening of the line circuit entailing a consequent closing of this traced circuit, the primary stepping magnet PM. is operated and advances the connector switch wipers CYW. one vertical step to directively locate a particularlevel of contacts in which level contacts of the called for line are located.

The slow releasing relay SRR. was operated on the first opening of the line circuit by the flow of current over the circuit just traced and being of the slow re leasing type maintained its armature attracted throughout the series of line circuit interruptions. At ESC, I show an escape magnet controlling the operation of the side switch wipers in the well-known way and, the mechanical arrangement is such that whenever an escape magnet is energized and thereafter denergized that upon such deenergization of the escape magnet the side switch wipers will ,be advanced to their next contact making position.

Then the relay SRR. attracted its armature 1t completed a circuit for the escape magnet ESC, the circuit including the source of current, the circuit being traced as follows. From the ground pole of the battery through normally opened contacts 41 of the relay SltR. through the winding of the escapermagnet E.S.C. a resistance coil RES. to the negative pole of the source of current. This will cause the energization of the escape magnet and upon the release of the armatureof the relay S.R.R. which occurs immediately after the sub scribers dial has come to rest, the escape magnet will advance its wipers to their second operative position. This release of the armature of the relay 8BR. occurs since at the end of the series of circuit interruptions the relay 25 will cause its armatures to be steadily attracted, thus steadily interrupting for a sufficient length of time contacts 28 in the circuit of the slow releas ing relay S.R.R. which will have time to release its armature and thereby cause the opening of the contacts 41 in the circuit of the escape magnet.

All of the side switch wipers are now in second position. The subscriber will thereafter again operate his dial causing a second series of interruptions of the line circuit and the relays 25 SR1. and SRR. operating as before, the same results will-be obtained except that the side switch wipers being in second position, the winding of the secondary stepping magnet SM. is substituted in the stepping circuit which in cludes the slow releasing relay S.R.R. and the secondary stepping magnet SM. will advance the connector switch traveling contacts along the previously selected level of contacts to directively locate the contacts belonging to the called for line. At the end of the second series of circuit interruptions the escape magnet will in the same manner as before described for advancing the side switch wipers from first to second position. will now advance the side switch wipers from second to third position. This will occur if the called for line upon whose contacts the connector switch wipers have come to rest is idle or unengaged. The narrative will be continued for the present with the assumption that the called for line is idle and therefore selectable.

In the third position of side switch wiper 42 encounters ground and thereby closes a circuit including the source of current for line magnet L.M. of the called line which thereupon will be energized attracting its armature, closing contacts C6. The contacts C6 being closed a circuit will be completed for the controlling operating magnet CL of the called line L.2, the circuit being traced from the ground pole of battery through normally opened contacts C6 of the line magnet L.M., normally closed contacts 43 of the set of springs located in the drawing to the left of, and under the control of the line magnet. L.M., normal contacts 4-4 and the winding of the controlling magnet CL. to the negative pole of the source of current. Current flowing over this circuit will'energize the controlling magnet C.L.

The escape magnet is also energized when the side switch wipers reach third'position, the energizing circuit being traced from the ground pole of battery through normal contacts 51 of the release magnet R.L., third position contact and wiper 52 of the side switch, the winding of the escape magnet, the resistance coil RES. to the negative pole of the source of current. The energization of the escape magnet will prepare the side switch wipers to advance into fourth position upon the later deenergization of the escape magnet as will later ap-' pear. The controlling magnet C.L.- of the called line switch circuit LS. 2 will interru pt itsown circuit at 44: in the manner previously described for the like magnet of the calling line and the armature of the controlling magnet C.L. will thereupon be retracted to latch .in the armature of the magnet L.M. to operate the set of springs I associated therewith and shown to the left thereof. lVhen this is done the contacts 4:3, 45, {i6 and 47 will be openand the contacts 49, 50 and 53 will be closed. The contacts 43 being open will open the circuit of the latching magnet CL.

The closing of the contacts 53 perform no function when the line is a called line. The opening of the contacts 45 opens the circuit of the line relay LR. to remove it from the line strands. The closure of the contacts 50 extends the severed line strand to a talking conductor 54:. The breaking of the contacts 46 opens the above described energizing circuit for the line magnet L.M. and places ground potential of the contact 20 of the connector switch. The breaking of the contacts 4-.7 removes the ground connection from the other talking strand. T he line strands now being extended through the line switch circuit to the connector circuit the ringing of the called subscribers station will now commence, the ringing circuit being traced as follows :from ground through third position contact and wiper 61 connector switch wiper and contact 18, one side. of the line L2 through the subscribers telephone bell '62, the other vside of the line, now closed line switch contacts 50, throughconnector switch contacts 19 and wiper resting thereonv through side switch will cause the operation of the ringing trip magnet 64 to close the contacts 68 thereof. The contacts 68 being closed will short circuit windingof the escape magnet E.S.C. to cause itto release the side switch wipers which will advance into fourthfposition thus opening the. ringing circuit just described and extending the talking conductors of the called line through fourth position contacts of side switch wipers 61 and 63 to the talking strands 22 and 23 of the connector switch circuit.

The usual impedance battery feed coils are shown connected to the called end of the talking-strands of the connector switch circuit, through which battery :current is suppliedto the called substation transmitter at B; Side switch wiper 52 advancing into fourth positionopens the circuit of the es fr The wiper 69 in fourth position conditions the release circuit for the'line switch LS. 2 as will be described later. Theside switch wiper 29 in advancing from third to fourth position opens the circuit of the slow releasing relay SR1. and short circuits a second winding laced upon the impulse relay 25. This for thepurpose of making im pulse battery relay 25 slow releasing so that the release of the connector switch H may not be accomplished by a momentary opening of the calling line circuit'such as might be occasioned by accidental operation of th calling subscribers dial at D. The subscribers are now in conversational circuit and it will be seen that at this time no current is flowing throughout the system involved'in this connection except the talkreceiver to the hook breaking the circuit of the line L1 to release the relay 25 in circuit with the line. When this relay is released a circuit is completed through ofi' normal contacts ON. for the release magnet BL. The-circuit being traced from the ground pole of battery through normal contacts 28 of the relay :25, normal contacts 32 of the relay SR1. through oii'normal 'contacts ON. of the switch through the winding of the release magnet RL. to the negative pole of battery.

The release magnet will attract its armatures opening the contacts 51 and closing contacts 70, 71 and 72. The contacts 72 being closed will produce a locking circuit for the release magnet BL. including oil normal contacts C.N., this to insure that the release magnet may remain energized until the switch mechanism has been fully restored to its normal position. The contacts and 71 being closed, ground is connected through the said contacts to the controlling magnet CL. of the two connected line circuits, to momentarily operate these controlling magnets, to release the latched in armatures.

Completed circuit for the magnet CL. of the calling line L-l may be traced from the negative pole of battery through the winding of the magnet CL. through now closed contacts 13 oft-he calling line switch, now closed contacts l of the set of contacts CS. 2 through the now closed contacts 71 of the release magnet BL. to the ground pole of the source of current. Current from the said source will energize the magnet CL. which will immediately attract its armature to unlatch any latched in armatures, and-in the case being described the armature A2 of the magnet LM. 2 and the armature A6 oi the magnet L1H. so that the sets' of springs controlled thereby, namely, the set CS. 2 and the set CS. 6 will be restored to their normal positions. Likewise will the controlling magnet CL. of the called line circuit be energized, its energizing circuit being traced from the negative pole of battery through its winding, connector switch contacts 21 and connector switch wiper 48, side switch wiper 69 and four a position contact thereof now closed contact 70 of the release magnet RL. to the ground pole of the source of current.

The magnet CL. being energized will unlatch the armature A-6 of the called line switch which controls the set of springs shown to the left of the magnet LM. of the called line which magnet in the first place controlled the latching oi": the armature A-6. This set of springs will also be restored to normal position'therei'ore in the case of the called line and the connector switch mechanism being restored to normal, the apparatus involved inthe preceding described connection may be again used to con'iplete another connection.

Reverting now to that point of the description where the assumption was made that the called for line was idle and therefore selectable, let us assume that the called for line was busy in which case the system is arranged to give a busysignal to the calling subscriber and to prevent a connection being made with the busy line whereupon the called subscdber may release the connection by restoring his receiver to the hook.

The above -functions are performed as follows, the side switch wipers at this stage of the operation being in second position as before described. It the called. for line is busy this will be evidenced by ground potential being placed upon the test contact such as the test contact 20 thereof, either by the closing of contacts 49 of the called line switch springs or by ground being placed upon the said contact 20 through the wiper of the connector switch engaging a multiple of the contact 20. the ground being applied thr ugh third or fourth position contacts or" a side switch wiper such as the side switch wiper s2 illustrated for the connector switch H. When such a guarding ground is en: countered upon the contact 20a circuit is completed for the test relay TB. of the connector switch circuit through second position contact of the side switch wiper 42. To operate the test relay TB; and to maintain the escape magnet E.S.C. energized the serial circuit for the escape magnet and the test relay TR. which is thereby formed may be traced as follows. From the guarding ground upon the test contact 20 of the called for line through the third wiper of the connector switch engaging the said contact through second position contact and wiper 42 of the side switch, normal contacts 73 and the winding of the test relay TR, nor- 1 contacts 7% of the relay SRR, the wmding of the escape magnet E.S.C. to the-negative pole of the source of current through the resistance coil RES. Thus he escape magnet is maintained energized prevent it allowing the side switch wipers escape into third position. Test relay TR. attracting its armatures will provide a locking circuit for the test relay winding an the escape magnet winding by the closure of contacts 75., the said circuit leading through the contacts and off normal contacts to ground.

The circuit of the secondary stepping magnet is broken by the opening of contacts 76 of the relay TR. so that any subsequent operation of the subscribers dial or short interruption of the line circuit will not operate the stepping magnet. The closure of the contacts 77 of the relay Tlii. connects a busy tone current to a talking strand ofthe connector switch circuit in the to to without departing from the spirit thereof and that where I have illustrated the device per 86 as applied to a particular system in a particular manner of use that it isby no means limited to such a system since other uses will readily be apparent tothose skilled in the art to which my invention apper tains.

What I claim as my invention is 1. In a telephone system, the combination with a plurality of telephone lines, a relay mechanism for each ofthelines for making connections with other telephone lines, a set of contact springs for the said relay mechanism for each of the other telephone lines adapted when operated to interconnect the said other telephonelines with one of the said telephone lines, an electromagnet for each of the said contact sets, a controlling magnet for the said relay mechanism, means to select one of the said contact sets upon the conjoint energization of the said con trolling magnet and one of the said ele-ctroi magnets and meansto deenergize the said controlling magnet to cause the said contact set to be operated. I a

2. In a telephone system, the combination with a plurality of-telephone lines, a relay mechanism for each of the lines "for making connections with other telephone lines, a set of contact springs for the saidrelay mechanism for each of the other telephone lines adapted when operated to interconnect one of the said other telephone lines with the of the said controlling magnet.

3. In a telephonesystem, a calling and a called telephone line, substations on the said lines, circuit interrupters at the said telephone line with the called telephone line,

animpulse relay associated with said switch having an armature adapted to, vibratein' unison with the said circuit interruptions to control the operation of the said switch, re

lease mechanism for the saidfswitch and controlling means independent of the called line substation for the said impulse relay to cause theimpulse relay to be slow releasing after the said impulse relay has controlled the" directive operation of the said switch and circuit connections thereafter operative when the calling substation retires to cause the said impulse relay to retract its armature to operate the said release mechanism.

4. In a telephone system a plurality of telephone lines, a line switch for each of the said lines, a plurality of trunk circuits for the said telephone lines, each trunk circuit terminating in multiple contacts oneach of the said; line switches, multipled nontraveling contacts for each of the said line switches, said last named multiple. contacts being terminals of the associated telephone line, a set ofline circuit terminalsbeing adapted to be interconnected with a set of trunk circuit terminals acontrolling ma net for the said line switcl1,.aselective elec tromagnet to select for interconnection a set of the said line circuit terminals and the cooperating set of trunk circuitterminals, means to simultaneously energize the said controlling magnet and one of the said selective electromagnets, means to subsequently deencrgize the said controlling magnet, and means responsive; to thesaid deenergi'za tion to cause the interconnection of the selected connected cont-act sets. g

'5. In a telephone system a plurality of telephone lines, a line switch for each of the' said lines, a plurality of trunk circuits for the said telephone lines, each trunk circuit terminating 1n multipled contacts on each of the said line switches, multipled non-traveling contacts for each of the said line switches, said last named multiple contacts being terminals of the associated telephone line, a set of line circuit terminals being adapted to be interconnected with a set of trunk circuit terminals, a controlling mag- 7 net for the said line 'switch,'a selective electromagnet to select for interconnection a set of the said line circuit terminals and the cooperating set or". trunkcircuit terminals, means to' simultaneously energize the said controlling magnet and one of the said selective electromagnets, means to subsequently deenergize the said controlling magnet means responsive to the said deenergization to cause the interconnection of'the selected connected contact sets. and meansto 6. In a telephone system a plurality of telephone lines, a line switch. for-leach of the said lines, a plurality of trunk circuits for the said telephone lines, each trunk circuit terminating in multipled contacts on each of the said line switches, multipled non-traveling contacts for each of the said line switches, said last named multipled contacts being terminals of the associated telephone line, a set of line circuit terminals being adapted to be interconnected with a set of trunk circuit terminals, a controllin magnet for the said line switch, a selective electromagnet to select for interconnection a set of the said line circuit terminals and the cooperating set of trunk circuit terminals, means to simultaneously energize the said controlling magnet and one of the said selective electromagnet-s, means to subsequently deenergize the said controlling magnet, means responsive to the said deenergization to cause the interconnection of the selected connected contact sets, means to cause the release of the selectively operated contact set upon a subsequent reenergization controlling electromagnet, and a pair of contacts included in the energizing circuit of the said controlling electromagnet to break the said energizing circuit whenever the controlling magnet is energized.

7. In system for selection, a common electroresponsiv'e motor device, a plurality of circuits therefor, contact terminals for the said circuits and a stationary connective device for interconnecting one of the said circuits with selected other of the said circuits, means operating under the conjoint action of said common electroresponsive motor device and one of the said stationary connective devices to mechanically latch-a set of said contact terminals of the said circuit in connection with the said selected other circuit, and an unlatching means responsive to a subsequent energization of the said common device to restore the said contact terminals.

8. In a telephone system a plurality of telephone lines, a group of trunk lines for extending the circuit from the said telephone lines to other telephone lines, a line switch for each of the said lines, means to cause the line switch of the calling telephone line to interconnect the said calling telephone line to an idle one of the said trunk circuits, mechanical means to maintain the said connection and electrical means for releasing the said connection.

9. In a telephone system in combination with a plurality of telephone lines, a line switch for each of the lines, a group of trunk lines for extending the circuit of the line conductors of the said telephone lines, elec trical means to operate the said line switch to connect its associated telephone line when calling, with an idle one of the said trunk circuits, mechanical latching means to maintai n thesaidconnection, an automatic means to disestablish the said connection upon a subsequent reenergization of the said electrical means.

10. In a telephone system, a telephone line, a line switch therefor, a group of the lines each having contact terminals in the said line switch, cooperating contact terminals for each of the first named contact terminal sets, said last named terminals being connected to circuit conductors of the first named line, electromagnetic means initially operated by line apparatus of the said line to interconnect a set of the said first named line contact terminals to a set of contact terminals connected to an idle one of the said group of lines and means to cause the release of an established connection by a subsequent energization of a porbeing under the control of the said impulse relay.

12. In a telephone system, telephone lines, relay mechanism for establishing connections between said lines, electromagnets and electrical contacts for the said relay-mechanism, substation apparatus on the telephone lines, a pair of talking conductors for each of the said telephone lines leading from the said substation apparatus to the said relay mechanism, means operated under the control of the said substation apparatus over the said pair of talking conductors to cause a pair of electromagnets of the said relay mechanism to be energized to operate se-' lected relay contacts to connect an associated telephone line with another of the said telephone lines, and a mechanical means common to all of the said relay contacts for locking the said relay contacts in their operated position.

13. In a telephone system, telephone substations, telephone lines for the said substations, each telephone line comprising a single pair of wires, relays controlled over the said pair of wires for establishing connect-ions between a substation on a calling line and a substation on a called line, a mechanical means common to a group of the said relays for holding the said relays in their contact operating position.

14. In a telephone system, telephone substations, telephone lines for the said substations, each telephone line comprising a single pair of wires, relays controlled. over the said pair of wires for establishing connections between a substation on a calling line and a substation on a called line, a

mechanical means common to a group of the said relays for holding the said relays in their contact operating position and automatic means forrestoring an operated set of relay contacts.

15. In a telephone system, telephone substations, telephone lines for the said substations, each telephone line comprising a single pair of Wires, relays controlled over the said pair of wires for establishing con nections between a substation on a calling line and a substation on a called line, a mechanical means common to a group of the said relays for holding the said relays in their contact operating position and automatic means for restoring an operated set of relay contacts, the said automatic means being under the control of the said substation over the said pair of wires.

16. In a selector switch a plurality of sets of selector contacts, individual operating means for each set, a selective controlling magnet for each individual operating means, a common controlling magnet and means operative responsive to the conjoint energization of the said common magnism tomake net and one of the selective magnets to operate a selected contact set.

17. In a selector switch a plurality of sets of selector contacts, individual operating means for each set, a selective con-;

trolling magnet for each individual operating means, a common controlling magnet and means operative responsive to the conjoint energization of the said common magnet and one of the selective magnets to op-' erate a selected contact set and means responsive to a subsequent energization of the said common magnet alone to restore operated contact set.

18. In combination with an automatic telephone switch mechanism, calling and called sub-station apparatus adapted to be inter-connected by the said mechanism, an

impulse relay to control setting-up operation of the said mechanism under the control of the said calling sub-station apparatus, the said impulse relay being of the fast operating type, and means responsive to the setting-up of thesaid switch mecha- FRANK M. SLOUGH.

the said relay of a slow oper- 

